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The present disclosure relates to a fall-back support for a luffing boom
which is attached to a boom head of a crane, having at least one pressure
rod which is arranged between the luffing boom and the boom head and
which bounds a fall-back movement of the luffing boom, wherein the at
least one pressure rod includes a fiber composite tube, in particular an
aluminum tube having a reinforcement of carbon fibers.

Inventors:

Streitz; Holger; (Ludesch, AT)

Assignee:

LIEBHERR-WERK NENZING GMBHNenzingAT

Serial No.:

075941

Series Code:

13

Filed:

March 30, 2011

Current U.S. Class:

212/293

Class at Publication:

212/293

International Class:

B66C 23/92 20060101 B66C023/92

Foreign Application Data

Date

Code

Application Number

Mar 30, 2010

DE

10 2010 013 328.0

Claims

1. A fall-back support for a luffing boom which is attached to a boom
head of a crane, having at least one pressure rod which is arranged
between the luffing boom and the boom head and which bounds a fall-back
movement of the luffing boom, wherein the at least one pressure rod
includes a fiber composite tube.

2. A fall-back support in accordance with claim 1, wherein the fiber
composite tube comprises an aluminum tube having a reinforcement of
carbon fibers, and wherein the pressure rod includes a plurality of
carbon fiber lamellae extending in a longitudinal direction of the
pressure rod.

3. A fall-back support in accordance with claim 2, wherein the carbon
fiber lamellae surround the aluminum tube in the peripheral direction
with intervals disposed therebetween.

4. A fall-back support in accordance with claim 2, wherein the carbon
fiber lamellae are arranged in a middle region of the pressure rod and do
not extend in the end regions of the pressure rod.

5. A fall-back support in accordance with claim 1, wherein the pressure
rod has a winding of carbon fibers in a partial region in a peripheral
direction.

6. A fall-back support in accordance with claim 5, wherein the winding of
carbon fibers extends beyond the region of the carbon fiber lamellae;
and/or wherein the carbon fiber lamellae are arranged on the winding of
carbon fibers.

7. A fall-back support in accordance with claim 1 having at least one
first end piece which allows a bolting of the fall-back support, and/or
having a second end piece which engages in a shape-matched manner in the
case of strain into an end receiver at the luffing boom or at the boom
head.

8. A lattice construction, comprising: a luffing boom; a boom head; and a
fall-back support for the luffing boom which is attached to the boom
head, the fall-back support having at least one pressure rod which is
positioned between the luffing boom and the boom head and which bounds a
fall-back movement of the luffing boom, wherein the at least one pressure
rod includes a fiber composite.

9. A crane, comprising: a luffing boom; a boom head; and a fall-back
support for the luffing boom which is attached to the boom head, the
fall-back support having at least one pressure rod which is positioned
between the luffing boom and the boom head and which bounds a fall-back
movement of the luffing boom, wherein the at least one pressure rod
includes a fiber composite.

10. The crane in accordance with claim 9, wherein a middle region of the
pressure rod experiencing a kinking force generated by the boom and head
geometry is reinforced by carbon fiber lamellae spaced apart from one
another around a periphery of the pressure rod, wherein each end region
of the pressure rod is free of the carbon fiber lamellae.

11. The crane in accordance with claim 10, wherein the pressure rod
further includes a carbon fiber winding extending over substantially the
length of the rod, except that a short piece at each end only is not
covered by the winding wherein the non-wound end regions amount to
respectively less than 5% of the rod length.

12. The crane in accordance with claim 11, wherein the carbon fiber
lamellae are positioned exterior to the winding of carbon fibers, and
wherein a fiber direction in the carbon fiber lamellae extend parallel to
a longitudinal direction of the rod.

13. The crane in accordance with claim 10, wherein the luffing boom is
arranged pivotably about a horizontal axis at the boom head, and wherein
the at least one pressure rod is positioned to take up forces on a
breakaway load or on violent wind gusts.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to German Patent Application No.
10 2010 013 328.0, entitled "Fall-Back Support", filed Mar. 30, 2010,
which is hereby incorporated by reference in its entirety for all
purposes.

TECHNICAL FIELD

[0002] The present disclosure relates to a fall-back support for a luffing
boom which is attached to a boom head of a crane, having at least one
pressure rod which is arranged between the luffing boom and the boom head
and which bounds a fall-back movement of the luffing boom.

BACKGROUND AND SUMMARY

[0003] Different solutions are known for the retention function of movable
or fixed luffing booms. On the one hand, in this respect, pull ropes
having a pressure support are used which are arranged on the front side
of the luffing boom and which bound the fall-back movement of the luffing
boom, for instance on a tearing of the load rope, for example. Such an
arrangement of pull rope and pressure support is also called a bird swing
colloquially. This solution, however, has the disadvantage that the crane
has to be positioned with a certain spacing from adjacent building edges
since the bird swing requires space to the front.

[0004] Furthermore, fall-back supports are known which have at least one
pressure rod which is arranged between the luffing boom and the boom head
and which thus bounds a fall-back movement of the luffing boom to the
rear. In this respect, pressure rods are manufactured from a steel tube
for such fall-back supports, which results in a high weight of the
construction and a correspondingly reduced payload of the crane. In
addition, only a relatively shorter boom can be erected due to the mass.

[0005] It is therefore the object of the present disclosure to provide a
fall-back support by which higher payloads can be achieved, in particular
by reducing the weight of the pressure rod.

[0006] This object is achieved in accordance with the present disclosure
by a fall-back support wherein the at least one pressure rod includes a
fiber composite tube, in particular an aluminum tube having a
reinforcement of carbon fibers. In this respect it is a case of a
fall-back support for a luffing boom which is attached to a boom head of
a crane, having at least one pressure rod which is arranged between the
luffing boom and the boom head and which bounds a fall-back movement of
the luffing boom. In accordance with the present disclosure, the pressure
rod in this respect includes a fiber composite tube. The use of such a
fiber composite tube as a pressure rod allows a substantial weight
reduction with an equal pressure resistance of the fall-back support. The
payload of the boom can hereby be correspondingly increased or a
correspondingly larger and longer boom can be used.

[0007] The pressure rod advantageously includes an aluminum tube having a
reinforcement of carbon fibers. The use of such an aluminum-carbon fiber
composite as a pressure rod results in a very strong and nevertheless
light pressure rod. In addition, the use of an aluminum tube allows an
easy connection of the pressure rod to the remaining construction, e.g.
via end pieces, which can be connected without problem to the aluminum
tube. The connection to the further construction, which is frequently
problematic with fiber-reinforced plastic tubes, is therefore
substantially simplified.

[0008] The pressure rod advantageously has a plurality of carbon fiber
lamellae extending in the longitudinal direction of the pressure rod. The
aluminum tube can be reinforced against buckling by the carbon fiber
lamellae so that the pressure resistance is substantially increased. The
fiber direction of the carbon fibers in the carbon fiber lamellae
advantageously likewise extends in the longitudinal direction of the
pressure rod.

[0009] Provision is advantageously made that the carbon fiber lamellae
surround the aluminum tube in the peripheral direction (e.g., around a
periphery of the rod) with intervals disposed therebetween. Weight can
hereby again be saved since no continuous carbon fiber reinforcement is
used which extends in the longitudinal direction of the aluminum tube,
but rather the carbon fiber lamellae each have a certain interval between
one another.

[0010] In this respect, a plurality of carbon fiber lamellae are
advantageously used which each surround the aluminum tube in the
peripheral direction with an equal interval from one another.

[0011] The use of carbon fiber lamellae also facilitates the manufacture
of the pressure rod in accordance with the present disclosure since they
can be manufactured separately and then connected to the aluminum rod.

[0012] The carbon fiber lamellae are advantageously arranged in a middle
region of the pressure rod and do not extend into the end regions of the
pressure rod. Weight can again also hereby be saved, while the middle
region of the pressure rod particularly prone to kinking is reinforced by
the carbon fiber lamellae. The length of the middle region with the
carbon fiber lamellae in this respect advantageously amounts to between
10% and 90% of the total length of the pressure rod, further
advantageously between 20% and 80%, further advantageously between 25%
and 70% and further advantageously between 30% and 50% of the total
length.

[0013] The carbon fiber lamellae further advantageously have a thickness
in the radial direction which amounts to between 50% and 300% of the wall
thickness of the aluminum tube, advantageously between 80% and 250%,
further advantageously between 100% and 200%.

[0014] Further advantageously, more than three carbon fiber lamellae are
provided, further advantageously more than five carbon fiber lamellae.
Further advantageously, the number of carbon fiber lamellae amounts to
between three and twenty, further advantageously between five and twelve.

[0015] Further advantageously, the pressure rod can have a winding of
carbon fibers at least in a part region in the peripheral direction. Such
a winding of carbon fibers allows a particularly effective damping of the
pressure rod.

[0016] The winding of carbon fibers in this respect advantageously extends
beyond the region of the carbon fiber lamellae. The winding of carbon
fibers in this respect advantageously extends over more than 50% of the
total length of the aluminum tube, further advantageously over more than
70%, further advantageously over more than 85%.

[0017] The thickness of the winding of carbon fibers in the radial
direction advantageously amounts to less than 70% of the wall thickness
of the aluminum tube and/or of the thickness of the carbon fiber
lamellae, further advantageously less than 50%, further advantageously
less than 30%. The thickness of the winding in this respect
advantageously amounts to more than 5% of the wall thickness of the
aluminum tube, further advantageously more than 10%.

[0018] Advantageously, no carbon fiber winding is provided in the end
regions of the aluminum tube.

[0019] Provision is further advantageously made that the carbon fiber
lamellae are arranged on the winding of carbon fibers. The pressure rod
thus has the following structure from the inside to the outside, each
layer contiguous with the adjoining layer: an aluminum tube, a layer
formed by the winding of carbon fibers in the peripheral direction and
the carbon fiber lamellae arranged on this winding.

[0020] The use in accordance with the present disclosure of an aluminum
carbon fiber composite tube allows a particularly simple connection of
the pressure rod via end pieces which are connected to the aluminum tube.

[0021] The fall-back support in this respect advantageously has at least
one first end piece which allows a bolting together of the fall-back
support. This end piece in particular has at least one lug with bore for
this purpose through which a bolt can be guided. Further advantageously,
the fall-back support has a second end piece which engages in
shape-matched manner in the case of strain into an end receiver at the
luffing boom or at the boom head.

[0022] The pressure rod can effectively bound or prevent the fall-back
movement of the luffing boom by these end pieces, e.g. for the case that
the load rope tears.

[0023] Further advantageously, the pressure rod in accordance with the
present disclosure has a compressive strength of more than 500 kN.

[0024] The pressure rod in accordance with the present disclosure cannot
only be used as a fall-back support for the luffing boom of a crane, but
can rather be used anywhere a high strength at low weight is required.

[0025] The present disclosure therefore furthermore includes a pressure
rod of an aluminum tube with a reinforcement of carbon fibers. Such an
aluminum tube with a reinforcement of carbon fibers can be used
everywhere high forces have to be taken up at low weight.

[0026] The pressure rod is advantageously designed in this respect as was
already presented above. The pressure rod in this respect in particular
has a plurality of carbon fiber lamellae extending in the longitudinal
direction of the pressure rod. The carbon fiber lamellae are in this
respect advantageously designed as was represented above.

[0027] The pressure rod further advantageously has a winding of carbon
fibers in the peripheral direction. This winding is advantageously in
this respect designed as was already represented above.

[0028] The fall-back support further advantageously has two end pieces
which re connected to the ends of the aluminum tube. These end pieces
advantageously serve the connection to the further construction.

[0029] The present disclosure furthermore includes a lattice construction,
in particular a boom, having a fall-back support and/or a pressure rod,
as was described above. The present disclosure in this respect in
particular includes a boom of a crane at which a luffing boom is
arranged, wherein, in accordance with the present disclosure, a fall-back
support in accordance with the present disclosure is arranged between the
luffing boom and the boom head. The present disclosure, however, also
includes lattice constructions very generally in which one or more
pressure rods in accordance with the present disclosure are used.

[0030] The present disclosure furthermore includes a crane having a
fall-back support and/or having a pressure rod and/or having a lattice
construction as was described above.

[0031] The present disclosure will now be described in more detail with
reference to an embodiment and to drawings.

BRIEF DESCRIPTION OF THE FIGURES

[0032] FIG. 1 shows an embodiment of a fall-back support in accordance
with the present disclosure in a side view.

[0033] FIG. 2 shows an embodiment of a pressure rod in accordance with the
present disclosure such as is used in the embodiment of a fall-back
support in accordance with the present disclosure.

[0034] FIG. 3 shows the pivotal connection of the pressure rod in
accordance with the present disclosure to pivotal connection points of a
crane as takes place with the fall-back support in accordance with the
present disclosure.

[0035] FIG. 4 shows a perspective representation of an embodiment of a
pressure rod in accordance with the present disclosure.

[0036] FIG. 5 shows a plurality of views of the embodiment of a pressure
rod already shown in FIG. 4. FIGS. 1-5 are shown approximately to scale,
although other proportions are possible.

DETAILED DESCRIPTION

[0037] A fall-back support in accordance with the present disclosure is
shown in FIG. 1. In this respect, the pivotal connection piece of a
luffing boom 1 is shown which is arranged via a boom head 3 at the main
boom 2 of a crane. Both the luffing boom 1 and the main boom 2 in this
respect comprise a lattice construction. The luffing boom 1 and the main
boom 2 are in particular composed of lattice pieces.

[0038] The luffing boom 1 is arranged pivotably about a horizontal axis 4
at the boom head 3. On a breakaway load or on violent wind gusts, the
luffing boom can be urged from the front to the rear, whereby very high
forces can arise in part. These forces have to be taken up by the
fall-back support.

[0039] The fall-back support shown in FIG. 1 in this respect has two
pressure rods 10 which are arranged between the pivotal connection piece
of the luffing boom 1 and the boom head 3. The pressure rods 10 are in
accordance with the present disclosure a fiber composite tube of an
aluminum tube and a carbon fiber reinforcement which can take up the
forces occurring on a load breakaway or on violent wind gusts despites
its weight, which is substantially lower in comparison with a steel tube.
The design of the pressure rods will in this respect be explained in more
detail further below.

[0040] In addition to the two pressure rods 10 in accordance with the
present disclosure, the fall-back support in FIG. 1 furthermore has two
hydraulic cylinders 6 which are coupled via gas springs and which are
arranged between the boom head 3 and the guying frame 5. The total
backward rotating torque of the guying frames 5 is thus compensated via
the gas springs 6. The backward rotating torque of the luffing boom is,
in contrast, taken up by the pressure rods in accordance with the present
disclosure which form rigid pressure rods.

[0041] The pressure rods 10 used in accordance with the present disclosure
in the fall-back support are shown in more detail in FIG. 2. The pressure
rod 10 in this respect has an aluminum-carbon fiber composite tube 20
which will be described in more detail further below. This
aluminum-carbon fiber composite tube 20 has end pieces 13 and 14 at the
ends which serve the connection to the luffing boom or to the boom head.
The end piece 13 in this respect has two lugs with a bore through which a
bolt can be conducted. The end piece 14, in contrast, has an opening 16
at the end side as well as a guide element 15. The pivotal connection of
the end pieces 13 and 14 is shown in FIG. 3 in this respect. The section
E-E shows how the end piece 14 is secured by a hook-shaped receiver 17
which is pivotally arranged at the boom head. The end piece 13, in
contrast, is bolted to the luffing boom via a fork-finger connection.

[0042] The fiber composite tube in accordance with the present disclosure
is now shown in more detail in FIGS. 4 and 5. The fiber composite tube
can, as shown above, be used as a fall-back support of a luffing boom.
However, equally, application possibilities result everywhere high
compressive forces have to be received with a light weight.

[0043] The pressure rod in accordance with the present disclosure in this
respect includes an aluminum tube 21 which has a reinforcement of carbon
fibers. In this respect, carbon fiber lamellae 23 are provided which
extend in the longitudinal direction of the aluminum tube. The carbon
fiber lamellae are in this respect arranged outwardly at the aluminum
tube and surround it in the peripheral direction, with a certain spacing
remaining between the individual carbon fiber lamellae. In this respect,
respectively the same carbon fiber lamellae 23 are used which are
arranged at regular intervals around the aluminum tube. In the
embodiment, eight carbon fiber lamellae are used.

[0044] As can be seen from FIGS. 4 and 5, the carbon fiber lamellae 23 are
arranged in a middle region of the aluminum tube and do not extend up to
and into the end regions. In the embodiment, the carbon fiber lamellae in
this respect have a length which corresponds to around 40% of the total
length of the aluminum tube 21. The carbon fiber lamellae are in this
respect arranged centrally with respect to the total length of the
pressure rod so that in each case approximately equally long regions
remain at the two ends of the pressure rod into which the carbon fiber
lamellae do not extend.

[0045] The composite tube in accordance with the present disclosure
furthermore has a winding 22 of carbon fibers. The carbon fibers are in
this respect wound around the pressure rod and thus form an effective
damping. The winding in this respect extends over a large part of the
total length of the aluminum tube 21. A short piece is only not covered
by the winding of carbon fibers at the two ends of the aluminum tube. The
length of the non-wound end regions in this respect in the embodiment
amounts to respectively less than 5% of the total length of the aluminum
tube.

[0046] The carbon fiber lamellae 23 are in this respect applied to the
winding 22 of carbon fibers. The fiber direction in the carbon fiber
lamellae extends parallel to the longitudinal direction of the aluminum
tube so that the kinking strength of the aluminum tube is substantially
reinforced by the carbon fiber lamellae. The aluminum tube in contrast
allows a particularly simple connection to end pieces via which the
aluminum carbon fiber composite tube can be connected to the further
structure.

[0047] In FIG. 5, the direction of the compressive force F is shown by the
arrows which acts on the pressure rod in accordance with the present
disclosure. The pressure rod in accordance with the present disclosure is
in this respect designed in the embodiment so that it withstands a
compressive force of more than 500 kN.

[0048] In the embodiment, the aluminum tube used has an inner diameter of
100 mm and an outer diameter of 110 mm. The aluminum tube thus has a wall
thickness of 5 mm. The outer diameter of the composite tube in the region
of the winding of carbon fibers in this respect amounts to 112 mm. The
carbon fiber winding thus has a thickness of 1 mm. In the region of the
carbon fiber lamellae, the tube in contrast has an outer diameter of 124
mm. The carbon fiber lamellae accordingly have a thickness of 6 mm. The
total aluminum carbon fiber composite tube has a total length of
approximately 2 m.

[0049] In this respect, it is obvious to the skilled person that the
dimensional data given above only relate to a specific embodiment of the
present disclosure which, however, enables a high compressive strength.
The corresponding dimensions for the aluminum tube, the winding and the
carbon fiber lamellae can, however, be adapted accordingly to other
applications.

[0050] The present disclosure with the aluminum carbon fiber composite
tube represents a particularly strong and nevertheless light pressure
rod. It can in this respect in particular be used in a fall-back support
in accordance with the present disclosure.

[0051] The present disclosure furthermore includes in addition to the
pressure rod and the fall-back support, lattice constructions such as a
boom in which they are used as well as a corresponding crane.